Raspberry Pi 4 Model B Revision 1.5 and U-Boot >= 2025.07 stalls issue.

[Matteo GUGLIELMI]

Hi Peter,

Thank you for your prompt reply.

I ran a git bisect between v2025.07 and v2025.10.

The first bad commit is:

bab54f5942c428be698216224fd10b91d974d4da
net: phy: Do not do CL22 phy reset before ethernet phy driver probe

Author: SkyLake.Huang skylake.huang at mediatek.com

On Raspberry Pi 4 Model B Rev 1.5 / board revision d03115:

   -

   v2025.07 works
   -

   after this commit, DHCP still works
   -

   small TFTP transfers still work
   -

   larger TFTP transfers, for example start4.elf, stall with repeated “T”

The bisect test was:

setenv autoload no
dhcp
tftpboot $loadaddr boot/vg3/boot/start4.elf # MY LARGE FILE FOR TESTING

The same test succeeds on good commits and fails on bad commits.

Thank you.

### BITSECT LOG ###

git bisect start
# status: waiting for both good and bad commits
# bad: [e50b1e8715011def8aff1588081a2649a2c6cd47] Prepare v2025.10
git bisect bad e50b1e8715011def8aff1588081a2649a2c6cd47
# status: waiting for good commit(s), bad commit known
# good: [e37de002fac3895e8d0b60ae2015e17bb33e2b5b] Prepare v2025.07
git bisect good e37de002fac3895e8d0b60ae2015e17bb33e2b5b
# bad: [a7d1214d2c9a38af3a9a1271dd8388068cba904c] bootstd: rauc: Fix
potential memory leak
git bisect bad a7d1214d2c9a38af3a9a1271dd8388068cba904c
# bad: [d1b6489ef11bc89145e9fcf1d0f05d89a934e410] kbuild: do not overwrite
.gitignore in output directory
git bisect bad d1b6489ef11bc89145e9fcf1d0f05d89a934e410
# bad: [8aa384d01a079ec2d816f7051a7208a337727338] expo: Rename x and y in
struct scene_obj_bbox
git bisect bad 8aa384d01a079ec2d816f7051a7208a337727338
# bad: [24e7625085ee14a55275e2fbdaa5e595af1d632f] patman: Add a helper for
managing cseries
git bisect bad 24e7625085ee14a55275e2fbdaa5e595af1d632f
# bad: [24776ab2766787d9629e7250486a0a662871b070] patman: Move Patch and
Review to patchwork module
git bisect bad 24776ab2766787d9629e7250486a0a662871b070
# good: [da24eb55327978410f5559f44ce1434ae8d8932d] Merge patch series
"BOOTP/DHCPv4 enhancements"
git bisect good da24eb55327978410f5559f44ce1434ae8d8932d
# bad: [f74c6f9a81de1c0c04c578b0e6e2d8b1303d6d43] u_boot_pylib: Improve
ANSI-colour output with backgrounds
git bisect bad f74c6f9a81de1c0c04c578b0e6e2d8b1303d6d43
# bad: [96b0a77da0e3877308effd3d916c779fb3deb9df] binman: Read the
skip-at-start value on startup
git bisect bad 96b0a77da0e3877308effd3d916c779fb3deb9df
# bad: [bab54f5942c428be698216224fd10b91d974d4da] net: phy: Do not do CL22
phy reset before ethernet phy driver probe
git bisect bad bab54f5942c428be698216224fd10b91d974d4da
# good: [44340456475da953a30c5cc4fbe8a9bc013c8c0f] net: tftp: don't call
stop callback from UDP handler
git bisect good 44340456475da953a30c5cc4fbe8a9bc013c8c0f
# first bad commit: [bab54f5942c428be698216224fd10b91d974d4da] net: phy: Do
not do CL22 phy reset before ethernet phy driver probe

On Mon, May 4, 2026 at 12:55 PM Peter Robinson <pbrobinson at gmail.com> wrote:

> Hi Matteo,
>
> > TFTP downloads in U-Boot >= 2025.07 on Raspberry Pi 4 Model B Revision
> 1.5
> > stall during transfer (continuous T output), while the same setup works
> > correctly with U-Boot 2025.04.
> >
> > Please note that U-Boot starts correctly, DHCP works, and small TFTP
> still
> > works, but large TFTP stalls (e.g., kernel or initramfs files).
> >
> > On the contrary, Raspberry Pi 4 Model B Revision 1.4 does not have the
> > stall issue and can download files correctly up to the latest stable
> > version of U-Boot (2026.04).
>
> As far as I can tell from PCN [1] the only difference is the dual RAM
> chips so I'm not sure what difference there may be and I only have rev
> 1.1 and 1.4 of the 4B. Any chance you could do a git bisect between
> 2025.04 and 2025.07 to work out what change causes the issue?
>
> Peter
>
> [1] https://pip.raspberrypi.com/categories/560-pcn
>